In ten years of frequent gunkholing on the Chesapeake I've had half the time on wing keels and half on a fin. I've grounded on both. Wind it comes to grounding they both have advantages over each other depending on the heel condition. Basically if you're motoring or sailing in very light winds, you're better off with the fin since in the worst case you can heel off. If you're sailing in strong winds, the wing gives you more warning by touching a wing tip and a better chance of getting out by dropping sail and leveling the keel.
Sailing heeled on the wing I have touched an edge several times and been able to get back out almost immediately. On the other hand the worst grounding I had was motoring a wing to an anchorage. It was very soft mud and she stood right up and could only be spun around but not moved otherwise. Fortunately we could just wait for high tide.
On a few other occasions I have motored a wing into one of those uncharted shoal spots and stopped in my tracks at 3 knots but not onto the shoal itself. Stopping at that speed is scary and not good for the boat or it's crew. We were still totally floating and could just turn or back from the shelf with no effort. We ran into the steep firmer mud instead of running up on it. I believe I've experience similar shoals with a fin which ended up slicing into the shoal and required much more expertise to get back off.
For the fin the worst case is sailing at full heel at a high tide. When she grounds you don't have much warning or more heel to work with. The momentum carries you further up the shoal and heels you even more ! In the motoring case I think you're better off with the fin since even if it slices in, you can heel it off if backing itself won't do. Plus you don't decelerate as fast with the generally smaller grounding surface area of the fin versus horizontal wing.
I find it interesting that the someone quotes the Navy study as favoring a bulb over a straight fin. I'd like to see the Navy's evaluation criteria since once on a shoal, he bulb has more surface area than the fin. I suppose they are assuming that the fin has deeper draft for the same righting moment so the bulb gets some plus points to offset the extra bulb surface area when trying to drag it off of a shoal. I helped someone with a bulb on a shoal once and it was not pretty. I previously had no problem getting my same depth fin off of the same shoal. If only we'd talked more the year between !
As far as sailing performance, the wing is a compromise between a deeper fin and a shoal draft. The performance can be expected to fall between the two also. The shoal draft has much more wetted surface than the deeper fin to get the same righting moment. Though a previous poster to this thread says the wing doesn't point as well that is contrary to what I've heard. What is clear is that the wing definitely pays a price off the wind with it's then useless extra wetted surface.
I haven't sailed much north of Annapolis, but I have gunked-holed to the edges of the chart clearances for my draft from Annapolis far south. All told, I think the skipper's experience and wisdom is more important than the type of keel. You need to know the strengths and weaknesses of each and when you are challenging these based on your current navigation. The less local knowledge I have, the more conservative is my navigation. That tends to keep me out of trouble more than the shape of the heavy thing under the boat.
Another performance related observation I've noticed is when tacking a wing and a fin. The wing can be made to dig the outer edge as you round the turn and turn sharper than the fin. With the wing you can actually make the boat heel outwards in the turn. Perhaps that's making too much turbulence and costing too much inertia. Tacking the fin I feel more like we're sliding around the turn. Not being a racer, I can't say if the ability to turn that sharp with a wing is an advantage in any way.
At this point I have a bias for the wing as I feel it best supports my cruising needs while giving better performance than the shoal draft. It lets me into shallower places than the fin and I'm not afraid of it. If I were a local racer I'd want the deep fin. Remember Australia II introduced the wing successfully as a rule beater against a comparable draft fin. If the two drafts are the same, the wing can beat the fin in some conditions. When heeled the wing acts like a deeper draft. If the Australia II had a shorter draft with the wing it would have lost. The cruiser case is the latter, a shorter wing draft versus a deeper fin.
Besides, when's the last time you even saw your keel ?